Auto-reload require files or local gems without restarting server in Rails development.
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Gemfile First commit. Sep 28, 2012


Gem Version

Auto-reload require files or local gems without restarting server during Rails development.

Currently, it supports Rails 3+ and above, including 3.1 and 3.2.

It uses ActionDispatch::Callbacks.to_prepare to reload the require files before each request. In Rails 3.2, it uses watchable_dirs to reload only when you modify a file. More details in this blog post.


Given a Gemfile

# Gemfile
gem 'my_gem',  :path => '~/work/my_gem'
gem 'my_gem2', :path => '~/fun/my_gem2', :module_name => 'MYGEM2'

To reload all local gems (the ones with :path attribute, or using local git repo):

# config/environments/development.rb
YourApp::Application.configure do

To reload a specific local gem: :my_gem

You can also reload a .rb file in lib or any directory: :half_baked_gem  # in lib dir :foo, :path => 'app/models'

The :path option is optional. In Rails 3.2, :path value is added into watchable_dirs. Rails 3.1 and 3.0 ignore this value.

The :module_name option is optional. By default, it is assumed that the top-level module is a CamelCase version of the gem name. If this is not the case, you can pass this option, a String. This value will also be picked up if included in the metadata of the gemspec, as in spec.metadata = {'module_name' => 'MYMOD'}.

RequireReloader adds lib into watchable_dirs. So, specify :path only if it is not specified in Gemfile and the file is located in other directory. :foo, :callback => lambda { |gem| puts "#{gem} got reloaded" }

You can supply a Proc with the optional :callback option. This proc gets called everytime after your gem got reloaded.


Add this line to your application's Gemfile:

gem 'require_reloader'

And then execute:

$ bundle


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Added some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request


This gem is forked from Colin Young's gem_reloader, based on a solution by Timothy Cardenas, inspired by a post from Leitch.


  • @sven-winkler: trigger callback after gem reloaded (issue #2)
  • @aceofspades: support gem metadata :module_name in Gemfile (issue #4)


  • v0.2.1: Add Rails 5.1 support (pull request from @kibenimatik)
  • v0.2.0: Support module_name option/spec-metadata
  • v0.1.6: RequireReloader::watch accepts :callback, runs it after gem reloaded (pull request from @sven-winkler).
  • v0.1.5: properly guess top-level module name based on gem name pattern, only watch git repo if it's local.
  • v0.1.4: remove 'vendor/gems' from watchable_dirs & autoload_paths, as local gem path is already specified in Gemfile.
  • v0.1.3: Skip reload local gem if it's itself; added integration tests.
  • v0.1.2: Minor rephrase on gem's description and summary.
  • v0.1.1: Use Bundler to fetch local gems info, instead of parsing Gemfile by hand.
  • v0.1.0: Forked colinyoung/gem_reloader, renamed & major rewrite to support Rails 3.2 and new features.
  • v0.0.2: Added "vendor/gems" to the config.autoload_paths so the user doesn't have to.